Clearing Operations (Narrative) (Details)	9 Months Ended
Clearing Operations (Narrative) (Details)	Sep. 30, 2026 USD ($) contract	Sep. 30, 2025 USD ($) contract	Dec. 31, 2025 USD ($)
Clearing Operations [Line Items]
Default fund contributions and margin deposits	$ 8,320,000,000
Payment for default funds and margin deposits	101,721,000,000	$ 70,866,000,000
Proceeds from default funds and margin deposits	102,501,000,000	$ 70,447,000,000
Liability due to market default	$ 0
Total number of derivative contracts cleared (in contracts) \| contract	56,315,700	55,697,783
Liability Waterfall
Clearing Operations [Line Items]
Junior capital, cash deposits and pledged assets	$ 16,000,000
Senior capital, cash deposits and pledged assets	16,000,000
Committed capital	72,000,000
Nasdaq Clearing Members Cash Contributions
Clearing Operations [Line Items]
Default fund contributions and margin deposits	2,530,000,000		$ 5,842,000,000
Restricted cash and cash equivalents
Clearing Operations [Line Items]
Gain (loss) currency translation adjustment	(80,000,000)
Investments
Clearing Operations [Line Items]
Gain (loss) currency translation adjustment	$ (167,000,000)
Minimum
Clearing Operations [Line Items]
Reverse purchase agreements, maturity range	1 day
Maximum
Clearing Operations [Line Items]
Reverse purchase agreements, maturity range	7 days
Nasdaq Clearing
Clearing Operations [Line Items]
Committed capital	$ 104,000,000
Power of assessment of the clearing member's contribution to the financial markets and commodities markets default funds (as a percent)	230.00%
Contract value of resale and repurchase agreements	$ 1,200,000,000
Total number of derivative contracts cleared (in contracts) \| contract	2,037,195	2,812,945